1. Field of the Invention
The present invention relates to a portable information terminal such as a portable telephone and a personal digital terminal, and in particular to a portable information terminal of a novel foldable structure that has an unprecedented function by further developing a foldable structure.
2. Description of the Related Art
Conventionally, a straight type and a foldable type have been used for the structure of a portable information terminal, particularly a portable telephone. Among others, a portable telephone of a foldable structure type has been widely used and the demand for this has expanded because it can be accommodated in compact.
A typical example of the foldable portable telephone, as shown in FIG. 1, is provided with a substantially oblong lower unit 100′ disposed with an operation section 102′ and an upper unit 200′ of substantially the same shape having a rectangular display section 202′, which are engaged together so as to be able to be freely opened and closed, by rotatably and axially connecting linear portions at respective one end of both units with a connection member 300′ such that a operation section surface 101a faces a display unit fitting section 201a. In general, a display unit has a sufficient length in its longitudinal axis direction in order to take a large display area. Further, the directions of a operation section and display contents are determined with respect to a state where the operation section is positioned downward (frontward) at the open time.
A portable telephone has come to be utilized as a portable information terminal that has additional functions of a browser of the Internet, an e-mail transmission/reception terminal, and a schedule management, not only communications. Therefore, the display contents are wide including large quantity of character information and images, and increase in sizes of a display unit has been progressed.
According to the conventional portable telephone of a representative foldable structure, it is necessary to set both upper and lower units to an opened state without exception at the time of looking at a display or carrying out a certain operation. It is necessary to open and close it frequently, which is troublesome and leaves room for further improving the handling.
Further, according to the conventional portable telephone of a representative foldable structure, display contents are displayed to match a vertically long display surface. Therefore, at the time of reading displayed characters, the number of displayed characters in one lateral row is small, resulting in many returns and therefore it has been difficult to read. Further, at the time of displaying a horizontally oriented image, it has been necessary to convert the image into a smaller image, or see the whole image by a horizontal scroll operation. This has a drawback in that the easiness of handling is lost.
Further, as a result of securing the end linear portion and the connection member, only a limited design can be obtained by leaving the end linear portion in the external shape, resulting in a problem of a small degree of freedom on design.
In addition to the portable telephone, similar problems generally exist in a foldable apparatus, like a PDA (Personal Digital Assistant), for example, having a display unit and a operation section disposed separately in two units that are connected to be freely opened and closed in a similar manner.
Prior proposals that are individually related to the above problems will be explained briefly. A “foldable portable electronic apparatus” is disclosed in Japanese Patent Application Laid-open Publication No. 11-30226, which tries to solve the above-described problem of the portable telephone of a foldable structure that it is necessary to open the upper and lower units in order to look at the display or carry out an operation, and it is not easy to handle the apparatus.
FIGS. 2A–2C show a foldable portable telephone described in the above publication No. 11-30226. FIG. 2A is a perspective view in an opened state, FIG. 2B is a perspective view that shows a usual folded state, and FIG. 2C is a perspective view that shows a reversed folded state. In each view of FIGS. 2A–2C, reference numerals and symbols corresponding to those used in this publication are attached with a prime symbol “′”.
In FIGS. 2A–2C, in the foldable portable electronic apparatus, a pivot 6′ that makes it possible to reverse the front and back of a casing 2′ at the display section is provided at a right angle to an axis portion 5a′ of a hinge 5′ that connects the casing 2′ at the display section side with a casing 4′ at the operation section side. With this arrangement, it is possible to fold the casing 2′ at the display section side by reversing it to expose the display unit 1′. This publication also discloses a structure that the pivot 6′ is provided with a rotation limiting mechanism that limits the rotation at a front and back reversing position, and a click stopping mechanism that holds a rotation limited state.
In addition to the above, Japanese Patent Application Laid-open Publication No. 11-215218 also discloses a “portable radio communication apparatus” that tries to solve a similar problem.
FIGS. 3A–3C show a portable radio communication apparatus described in the above publication No. 11-215218. FIG. 3A is a perspective view in a state that a casing at a display side is rotated in an opened state, FIG. 3B is a top plan view that shows a first posture that the apparatus is closed with the display set to the inside, and FIG. 3C is a top plan view that shows a second posture that the apparatus is closed with the display exposed to the outside. In each view of FIGS. 3A–3C, reference numerals and symbols corresponding to those used in this publication are attached with a prime symbol “′”.
In this publication, a hinge section 5′ structured with a ball joint, for example, is used to connect a second casing (a casing at a display section) 6′ provided with a display 7′ to a first casing 1′ that forms a pair with the second casing so that they can be freely opened and closed and supported to rotate relatively in an opened state. With this arrangement, a portable radio communication apparatus 10′ is allowed to be closed with the second casing 6′ reversed.
In addition to the above, Japanese Patent Application Laid-open Publication No. 2000-353030 proposes an “open/close type portable information terminal” such as a portable telephone that makes it possible to look at a display or carry out a simple operation without setting the upper and lower units to an opened state. According to this open/close type portable information terminal, a display section casing having a display section and a operation section casing having a operation section are structured to be able to rotate freely by connecting respective one end of both casings with a rotation mechanism in a state that a display section surface faces the same direction as that of a operation section surface. Operation keys that make it possible to look at the display section in a closed state, and carry out an operation in a closed state are provided in the display section casing. With this arrangement, it is possible to carry out a simple operation in a closed state.
A technique for solving the other problem that it is difficult to read sentences is disclosed in Japanese Patent Application Laid-open Publication No. 2001-156893. This technique is designed as a communication display system to be provided with a display unit section that can rotate a liquid display unit from vertically oriented to horizontally oriented and vice versa, and a display switching section that changes over a display of the liquid display section from vertically oriented to horizontally oriented and vice versa in synchronization with the rotation of the display unit section.
According to this arrangement, a rotatable display unit section is fitted to a main body in the case of a bar-type portable telephone, and is fitted to an upper unit of a main body in the case of a foldable portable telephone. In both cases, the rotatable display unit section is axially supported rotatably in a plane parallel with a main body surface. In order to improve its operability, this publication also proposes a structure that a operation button is provided on a main body of the communication apparatus that appears after the display unit section has been rotated from vertical orientation to horizontal orientation.
Further, Japanese Patent Application Laid-open Publication No. 7-202748 discloses a portable radio apparatus having a display section that does not rotate but having a casing simply divided into two flat casings which overlap each other and connected rotatably along a plane parallel to the flat surface thereof, allowing the casings to be folded when not used, resulting in improved portability.
Furthermore, Japanese Patent Application Laid-open Publication No. 5-211547 discloses a portable telephone also having a fixed display section, in which a casing having a transmitter is rotatably and axially supported relative to a main casing, and a connection surface of both casings is formed in a curve. With this arrangement, when opened, a receiver and the transmitter are in a distance and at an angle suitable for communications.